Safety switch



F. W. MURPHY SAFETY SWITCH June 1, 1954 Filed July 7, 1952 INVENTOR Franic WMur vhy BY MQLM l I I ATTOR NE Y5 Patented June 1, 1954 UNITED STATES SAFETY SWITCH Frank W. Murphy, Tulsa, Okla. Application July 7, 1952, Serial No. 297,474

1 Claim. 1

This invention relates to a safety switch for use in controlling the operator for a pump.

In a well pump, such as a pump for irrigation systems or the like, where a substantial drop ocours in the water supply which results in the pump running without drawing any water, considerable damage may result in the pumping apparatus before the pump is shut down. It is, therefore, an object of this invention to provide an electrical switch connected to the pump operator which under normal pumping conditions will be in circuit closing condition. The switch embodied in this invention is such that if the volume of water being pumped should drop below a safe margin, the operator will be stopped this invention is to provide a safety switch structure which can be initially set so as to start the pump operator in operation, and after the pump has been in normal operation the manual setting will be released so that continued operation of the pump will be under automatic safety conditions.

With the above and other objects in view, my invention consists in the arrangement, combination and details of construction disclosed in the drawings and specification, and then more particularly pointed out in the appended claim.

In the drawings:

Figure 1 is a detailed side elevation of a safety switch constructed according to an embodiment of this invention mounted on a water pipe or duct for controlling the pump operator connected with the duct.

Figure 2 is a vertical section of the switch or regulator for the operator.

Referring to the drawings, the numeral I designates generally a pipe or duct which is connected between a pump and a well or water supply wherein the pump is operated by means of an operator II which may be an electric motor, or other operator.

In order to provide a means whereby the operator II will be stopped when the water in the pipe or duct I0 drops either below a predetermined level or becomes dry, I have provided a spring-pressed switch I2 which is interposed in the conductors I3 and I4 connected with the operator I I.

The switch I2 is spring-pressed to a normal circuit closing position so that the operator H may operate the pump for drawing water through the pipe or duct Ill. The switch I2 is carried by a support I5 which extends upwardly from a diaphragm housing generally designated as l6.

The diaphragm housing I6 includes upper and lower housing members I1 and I8, with a flexible diaphragm I9 secured between the housing members H and I8. The lower housing member i8 is formed with a boss 20, and the upper end of a pipe 2! is secured in the boss 20.

A scoop 22 is threaded onto the lower end of the pipe 2i and the scoop 22 is mounted in opposed relation to the direction of movement of the water in the pipe I 0 so that as the water moves to the right, as viewed in Figure 1, the water will enter the scoop 22 and rise upwardly in the pipe 2| so as to thereby place the trapped air in pipe ZI and in the space below the diaphragm it under sufficient pressure so as to flex diaphragm I9 upwardly.

A lever operating rod 23 is secured at its lower end to the diaphragm I 9 and slidably engages through the upper housing member operating lever 24 is rockably mounted on a pivot 25 and is formed with an opening 26, through which the rod or bolt 23 loosely engages.

A pair of nuts 21 and 28 are threaded onto the bolt or rod 23 on the lower and upper sides of the lever 24 so that the lever 24 may be regulated as to its movement according to the movement of diaphragm I9 and bolt 23. Switch I2 includes a downwardly projecting switch button 29 disposed in the path of the rocking movement of the short lever arm 30 of lever 24.

A spring IN is interposed between the lever arm 3t and the upper housing member I! so as to constantly urge arm 30 upwardly to circuit breaking position, with arm 30 pushing button 29 upwardly. The outer end of lever 24 is formed with a keeper notch 32, within which a manually adjustable latch member 33 is adapted to initial- ].y engage.

The latch member 33 is mounted on a pivot 34 extending between a pair of upstanding ears 35 carried by the upper housing member I1, and a spring 35 constantly urges the latch member 33 outwardly to released position. A latch operating pin 37, which is spring-pressed outwardly by means of a spring 38, is carried by a hood or cover 39 and is adapted to be manually pushed inwardly for rocking latch member 33 inwardly to engagement with the keeper 32.

When latch member 33 is engaged with keeper 32, lever 24 will be rocked upwardly on its long end and short lever arm 30 will be rocked downwardly so that the switch button 29 may move downwardly to circuit closing position. At this time, pump operator Il may be operated in the normal manner, and after a flow of water has I1. A switch been established in pipe 10 so that pressure in pipe 2| will flex diaphragm l9 upwardly, lever 24 will be raised upwardly by flexing of diaphragm l9 and latch member 33 will be released from keeper 32 so that continued operation of operator H-will be under safety conditions.

In the event, after initial starting of operator E l, the flow of water in pipe [0 should be stopped, diaphragm 19 will be released from air pressure on the lower side thereof and will flex downwardly and, in addition, spring 3| will swing short lever arm 30 upwardly to engage switch button 29 and move switch 12 to a circuit breaking position.

With a safety switch as hereinbefore described the switch may be mounted at any-point in the water duct, such as an irrigationcanal or the like, and if the Water should be exhausted in the canal or duct, the pump which is connected with the canal will be promptly stopped so that the pump will notbe damaged bydry operation.

I do not mean to confine myself to the exact details of construction herein disclosed, but claim all variations falling within the purview of the appended claim.

A safety switch for a pump operator which includes a liquid duct, a vertical pipe projecting into said duct, and a scoop at the lower end of said pipe; said switch comprising a diaphragm housing at the upper end of said pipe, a flexible diaphragm in said housing, a normally closed switch carried by said housing, a spring-pressed lever rockably carried by said housing and constantly urging said switch to circuit breaking position, releasable latch means for holding said lever disengaged from said switch, and means connected with said diaphragm and engageable with said lever to effect release of said latch means by presence of a predetermined liquid level in said duct.

References Cited in the file of thi patent UNITED STATES PATENTS Number Name Date 1,45l,064= Dunajeff Apr. 10, 1923 2,119,783 Harrington June 7, 193?, 2,293,574 Teach et al. Aug. 18, 1%2 2,339,957 Smith Jan. 25, 1944 2,440,981 Smith May 4, 19-l8 2,473,726 Payne June 21, 1949 

